A technique to detect a load current by using a source-drain voltage of a MOS transistor has been disclosed conventionally.
In a MOS transistor, a source-drain voltage differs depending on a direction of flowing of a drain current, even for an identical value thereof, due to its parasitic diode. Hence, a correspondence relationship between a voltage of a MOS transistor and a drain current is changed depending on a direction of a current so that linearity is not maintained. An attempt to switch a current detection circuit depending on a direction of a current that is supplied to a load has been executed but a configuration of such a current detection circuit is complicated and its cost is increased. A current detection circuit is desired that is capable of detecting a drain current readily and accurately even in a case where a direction of such a drain current that flows through a MOS transistor is changed.